Greetings, Advice on Kevlar Canoe Referb

-- Last Updated: Jul-17-15 7:44 PM EST --

Greetings Paddlers,

I found this site while searching for information on how to refurbish a boat I bought for $75, twenty years ago. We used it a quite a bit, then it went to a friend for storage and a little repair. Unfortunately it was not stored well (upright, outside in weather) and the only repair was some bondo which I am working to remove.

Anyway, the only labeling on it is "Sawyer Canoe Company Oscoda, MI", "Kevlar 49" and the s/n "SAW 015210680" Its the original Kevlar tan color, 18` long, 36" wide at the gun wall, flat bottomed, with two farm-tractor style seats, the same color and material as the body. From what I have read of other posts on this forum, that seems to be the information people are looking for to help ID a boat.

An exact ID on the model is probably not necessary though for my goal though I am curious. My goal is to get it sea-worthy and looking good. Based on the fact that it is natural Kevlar color inside and out, I am assuming (correct me here?) that the boat is purely Kevlar in construction (i.e. no fiberglass, carbon fiber, etc.) For this reason I would like to refurbish it using kevlar vs. fiberglass, unless there are strong reasons not to.

The primary damage appears to be two fold. Both the bow and stern are smashed up pretty bad and the foam that fills the (flotation?) cavities is visible and crumbling and probably should be replaced. (I am thinking spray-in low-expansion foam insulation. The kind that comes in an aerosol can. Yes/No?)

In addition, there are several cracks or tears visible along the chine at various points, most are irregular, three to four inches long. They all seem to start at about that the center point of the curve and moving up from there. Some run fore-to-aft as well. These cracks are visible inside on out and seep water, There also appear to be some cracking along the inside of the body where the flotation chambers meet the floor of the boat, both fore and aft, and there are one or two at random points on the bottom of the boat.

So my main question here is, is there a good book, or on line resource for how to refurbish such a craft? Something that can answer most of my questions? Otherwise, I'll have to beg all of your pardon as I come here with lots of questions as I go along.

One question I have right now just based on the reading I have done is this: I see frequent statements about how you can't sand Kevlar and that doing so “fuzzes” it. People seem to use this as a rational for using fiberglass to repair Kevlar boats. What I am failing to grasp is what is the implications of this fact? Why is not being able to sand Kevlar a problem? Shouldn't I only ever be trying to sand off excess resin?

Thank you in advance for any help.


You want a fuzzy boat?

The Epoxy Book
A publication available as a free download will give you some good tips on fiber glassing and general epoxy work. It is published by System Three, a major epoxy manufacturer, but the info pertains to the use of any epoxy. It is available here:

I don’t know as much about Sawyers as some others who post here, but your dimensions and description fit those of the Sawyer Guide Special. I don’t know what type of layup Sawyer was using back in 1980, but all Kevlar boats were more common then than they are now. However, fiberglass, when fully wet out with a resin that cures clear, can be nearly transparent so you cannot necessarily be sure that there is not an exterior layer or two of fiberglass.

I would be very careful with the expanding foams. I have heard some stories of people ruining boats with that stuff because the foam soaked up water. I don’t know if that is true for all of them or how to distinguish. If there is any way to remove the foam, or some of it, and seal the edges of the float tanks I would try that. If you can, you will need to drill a small hole and put a vinyl cork in it, or an even smaller hole and run a stainless steel screw into it, to allow air pressure to equalize with temperature and elevation changes.

A general rule when applying a patch to a composite boat is to sand the area of repair until you can see fibers so as to assure a good bond to the underlying fabric. Yes, you can sand Kevlar some and generally you are just sanding the resin initially. When you get down to the fibers is when the surface will start to get rough. This is not such a big deal if you are planning to apply a patch over the roughened area.

Another general rule is to use Kevlar or some other aramid for interior patches and fiberglass on the exterior. Kevlar fibers are much stronger in tension than compression and less strong than comparable sized fiberglass fibers in compression. Fiberglass has a lower strength to weight ratio generally but is more equally strong in compression and tension. And fiberglass patches, unlike Kevlar, can be feathered very smooth at the edges. They will also be much less conspicuous then Kevlar patches because they wet out nearly clear and allow the underlying fabric to show through. So fiberglass is better used on the exterior.

You could use fiberglass for interior patching as well but it would be a bit heavier than aramid. Fiberglass tape (available in multiple widths) is convenient to use because it does not fray along the edges, and might be a good bet to use to seal up the flotation tanks. Fiberglass is also significantly cheaper than aramid.

Using peelply over patches, especially aramid, will yield a smoother patch edge without the need for sanding, or as much sanding.

I have sanded our kevlar boats…
…many times.

Just don’t sand into the Kevlar cloth

When refinishing a hull or adding a patch, I just sand the epoxy finish.

If you sand into the cloth, it will create the fuzzies which are very difficult to refinish

Jack L